ProjectileMotionforChunkers | projectiles thrown to get good estimates

ProjectileMotionforChunkers is a Java library. ProjectileMotionforChunkers has no bugs, it has no vulnerabilities and it has low support. However ProjectileMotionforChunkers build file is not available. You can download it from GitHub.

A simulator for projectiles thrown to get good estimates of distance with wind resistance and Magnus effect. Copyright (c) 2012 Luke Van Hulle Contact BeardedOne85@gmail.com. Purpose: This project is designed to accurately simulate shots of pumpkins at velocities from near zero to approaching Mach 1, 340 meters/second, 760 miles/hour by taking into account both the coefficient of drag (wind resistance) and the coefficient of lift (Magnus Effect, excellently introduced here ). Most people are familiar with wind resistance but the Magnus Effect is less widely known. Basically the Magnus Effect causes a force on a rotating object that is moving through a fluid. It is what causes golf balls to hook and slice or what causes a ping pong ball to dive with top spin. The Magnus Effect is also what causes Hop-Up in airsoft guns, which may be of particular interest to air cannon Chunkers. (Please note that the Magnus Effect is NOT related to Bernoulli's Principle where faster air has lower pressure, slower air has higher pressure.) What is fortunate for a Chunker is that a sling on a trebuchet, maganel, etc, puts back spin on the projectile which causes lift. Although this extra lift does allow for greater distance it has the largest effect on the Optimum Launch Angle, lowering it considerably from the theoretical optimum of 45 degrees. LDVance, a high school physics teacher, trebuchet enthusiast, and talented modeler told me that in his observations the coefficent of lift tends to be around 0.09(it is a scalar so no units necessary) so that is the default value I have used. Understanding the Graphs: Optimum Distance vs Velocity Variables: The upper and lower velocities for the X axis. What it shows: This graph shows the maximum distance a shot can go for a range of initial velocities. With the given initial velocity, the X axis, the shot's optimum launch angle is found and the distance of that shot is used as the corresponding Y Axis location Use: This graph would be used when you have a distance goal for your machine and you want to know how fast your projectile will have to go to get it there. This graph can also be used if you have a weight and height idea for your trebuchet and want to know how far your projectile will go. Potential Improvements: More accurate Coefficient of Drag calculation. Cross Hairs for the graphs to allow more accurate readings at various points Ability to type in desired data values instead of using the up/down buttons Ability to save graphs to a pdf (this one would be pretty easy for Processing) Ability to remember previous data values so the graphs start with them the next time the program is started Lower processor demand Graph energy requirements/list energy lost due to friction Graph deceleration along flight path. Assumptions: Round projectile Buoyancy is negligible, ie items are not near, or for that matter even 10%, the density of the fluid in which they are traveling Coriolis Effect is negligible, your projectile is traveling less than 100 miles The program does not allow for backwards shots, even with a launch angle less that 90 degrees the Coefficient of Lift can cause the shot to go backwards The projectile is not perfectly smooth The roughness on the projectile is uniform The air immediately encountered upon release is stationary. This would not be true for an air cannon although the difference probably is probably negligible. Useful things to know: If you want to test a shot without wind resistance set the air density to Zero. Development Software: This program was written in Eclipse v3.4.2 using the Processing (v1.5.1) add-on Proclipsing (the Beta version I believe). Works Cited: *Areodynamics of a Sphere and an Oblate Spheroid for Mach Numbers from 0.6 to 10.5 including some effects of Test Conditions M. Leroy Spearman and Dorothy O. Braswell August 1993